1. Field of the Invention
The present invention relates to preparation of polychlorinated pyridine mixtures by direct liquid phase chlorination of 3,5-lutidine or 3,5-lutidine hydrochloride. Typical of the products produced are 2,3,5,6-tetrachloropyridine; 5,6-dichloro- and 2,5,6-trichloro-3-trichloromethyl pyridine; 3,5-bis(trichloromethyl)pyridine; and 6-chloro- and 2,6-dichloro-3,5-bis(trichloromethyl)pyridine. These products have utility, for example, as intermediates for herbicides and insecticides. A further aspect of the present invention relates to further chlorination of mixtures rich in 3,5-bis(trichloromethyl) and 6-chloro-3,5-bis(trichloromethyl)pyridine to form 5,6-dichloro-3-trichloromethyl pyridine and/or 2,3,5,6-tetrachloro pyridine, and the further chlorination of mixtures rich in 6-chloro-3,5-bis(trichloromethyl)pyridine and 2,6-dichloro-3,5-bis(trichloromethyl pyridine to form 2,5,6-trichloro-3-trichloromethyl pyridine.
2. Description of the Prior Art
The utility of 2,3,5,6-tetrachloropyridine as an intermediate to insecticidal compositions is set forth in Dietsche et al U.S. Pat. No. 4,256,894.
Brewer et al U.S. Pat. No. 3,732,230 discloses liquid phase chlorination of 3,5-lutidine at 100.degree. C. and 120.degree. C. with greater than 30 psig of HCl partial pressure to yield unspecified polychlorinated lutidines.
Nishiyama U.S. Pat. No. 4,184,041 describes the utility of 5,6-dichloro-3-trichloromethyl pyridine in the production of herbicidal compositions.